1. Field of the Invention
The invention relates a system and a method for continuously manufacturing liquid crystal display panels. More specifically, the invention relates to a system and a method for manufacturing liquid crystal display panels by a process that includes sequentially bonding first and second polarizing plates, which are drawn and supplied from first and second polarizing plate rolls, respectively, to both surfaces of a liquid crystal cell to form a liquid crystal display panel; and optically inspecting the liquid crystal display panel.
2. Background Art
A system for continuously manufacturing liquid crystal display panels is disclosed, in which first and second polarizing plates, which are drawn and supplied from first and second polarizing plate rolls, respectively, are sequentially bonded to both surfaces of a liquid crystal cell to form a liquid crystal display panel (Japanese Patent Application Laid-Open (JP-A) No. 2005-37417). An apparatus for inspecting liquid crystal display panels is also disclosed, in which light is irradiated to one side of a liquid crystal display panel, and light transmitted through the liquid crystal display panel is imaged at the other side of the liquid crystal display panel (JP-A No. 2007-256106).    Prior art document: Japanese Patent Application Laid-Open (JP-A) No. 2005-37417 and Japanese Patent Application Laid-Open (JP-A) No. 2007-256106.
In view of continuous production of high-quality liquid crystal display panels, it is advantageous that bonding means and inspection means placed in a series of feed lines (in a continuously line) for feeding a liquid crystal cell and a liquid crystal display panel are used in a process including bonding polarizing plates to both surfaces of a liquid crystal cell and then quickly performing optical inspection of the liquid crystal display panel. This is because when the process is performed in the continuous line with the bonding speed and the inspection speed set equal to each other (or with the inspection speed set higher than the bonding speed), the liquid crystal display panel is prevented from waiting for a long time for the inspection after the bonding process, so that high-quality liquid crystal display panels can be continuously produced at high speed.
According to findings by the inventors, when a bonding process and an inspection process are performed at high speed in a series of feed lines (in a continuous line) for feeding a liquid crystal cell and a liquid crystal display panel, non-defective products with no quality problem are sometimes misjudged to be defective in the inspection process. It has been found that as a result of re-inspection of such liquid crystal display panels determined to be defective, they are determined to be non-defective. This is considered to be because during the bonding of the polarizing plate, the liquid crystal cell is electrostatically charged so that the alignment of the liquid crystal molecules are changed, and due to such an effect, the product, which has been once determined to be defective in the inspection process performed in the continuous line, regains the aligned state of the liquid crystal molecules after a lapse of time, and is determined to be non-defective when re-inspected in such a state.
This problem is a new problem with high-speed continuous production of liquid crystal display panels, which is caused by a process in which a bonding process with bonding means and an inspection process with inspection means are performed at high speed in a series of feed lines (in a continuous line) for feeding a liquid crystal cell and a liquid crystal display panel.